Open CarsonPruitt-NOAA opened 1 year ago
Below is an analysis on the Water Surface Elevation (WSE) comparisons between ras2fim VS HAND run for 12090301. The analysis is performed on the rating curve points derived from ras2fim run (_reformat_ras_rating_curvepoints.gpkg file). Below we see a map of the ras models points on the DEM from HAND run:
The ras WSE is directly obtained from ras rating curves file (_reformat_ras_rating_curvetable-12090301.csv) for the maximum discharge value. HAND WSE is computed by summing the two items below:
Below we see some plots comparing the two methods to estimate WSE. Roughly speaking, HAND WSEs are 1.8m higher than ras WSE (RMSE=1.8m):
The "error" --difference between ras and HAND-- is higher for low WSE values:
If we use the 'precalb_discharge_cms' instead of 'discharge_cms' the plots change to
The idea is to update the HAND SRC using ras2fim results as explained below:
Instead of converting the ras2fim rating curve to stage, you should:
Note: Apply above methodology only when HAND minimum WSE is higher than ras2fim minimum WSE.
The goal is to update HAND SRC using ras2fim points results as explained below:
The above methods to update HAND SRC are evaluated using the max flow of ras2fim rating curves. For each ras2fim point, “Error” is computed as the difference between maximum WSE from ras2fim rating curve and HANDs interpolated WSE for max flow of ras2fim. The adjustment methods are applied only when original HAND max WSE is higher than ras2fim max WSE.
Error reduction is computed using Equations below:
On ras2fim points level, as we showed earlier, RMSE of the original error is 1.803m. The error is reduced to 1.789m and 1.756m for Method1 and Method2, respectively. This is 0.8% and 2.64% error reduction for Methods 1 and 2, respectively.
Also, we can aggregate the errors of ras2fim points for each HAND HydroID by applying RMSE equation. Plot below compares error reduction percentages between the two methods:
Use the maximum discharge from the exported ras2fim rating curves to feed into the HAND rating curves and compare the two WSE. We hope to see an insignificant difference between the two, but this evaluation will determine if we need to take another look at the calibration technique.